Conventionally, there is known a so-called built-up wiring substrate in which plural wiring layers and plural insulating layers are alternately layered one on top of the other, and adjacent wiring layers are connected to each other by way of a via hole penetrating an insulating layer sandwiched between the adjacent wiring layers.
In a case of connecting a semiconductor chip to the built-up wiring substrate by using a flip-chip method, the semiconductor chip and the built-up wiring substrate are connected by forming bumps on corresponding electrode pads of the built-up wiring substrate and the semiconductor chip, and bonding the corresponding electrode pads of the built-up wiring substrate and the semiconductor chip.
As described, in, for example, Patent Document 1, the process of forming bumps on the side of the built-up wiring substrate is proposed to be omitted by having the electrode pads of the built-up wiring substrate protrude from a surface of the built-up wiring substrate. In this case, bumps are formed only on the side of the semiconductor chip. Thereby, the bumps formed on the semiconductor chip can be bonded to the electrode pads of the built-up wiring substrate.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-196860
In the process for forming electrode pads that protrude from the surface of the built-up wiring substrate, recess parts are formed by etching a support body that is used during the manufacturing of the built-up wiring substrate. Then, electrode pads are formed in the recess parts. Then, the support body is removed. Thereby, the electrode pads that protrude from the surface of the built-up wiring substrate can be formed into shapes corresponding to the shapes of the recess parts.
However, in the case of forming the recess parts, the depths and widths of the recess parts may become different from each other because the recess parts are formed by etching the support body. Thus, the shapes of the recess parts may vary. This also causes the shapes (e.g., height, width) of the electrode pads to vary. As a result, the bonding strengths become different among the electrode pads when mounting the semiconductor chip on the built-up wiring substrate. This leads to degradation of bonding strength (i.e. bonding reliability) between the electrode pads and the semiconductor chip.